High frequency electron discharge device tuning means having means to convert from rotational to reciprocating motion



Jan. 24, 1967 J. A. BROWN 3,300,679

HIGH FREQUENCY ELECTRON DISCHARGE DEVICE TUNING MEANS HAVING MEANS TOCONVERT FROM ROTATIONAL TO RECIPROCATING MOTION Filed Aug. 26, 1964"OUTPUT CAVITY DRIVER CAVITY 2 3 TUNER SHAFT REVOLUTIONS UNCOMPENSATEDCOMPENSAT (SO WMONEIHOB HA INVENTOR.

JACK A. BROWN BY m;

ATTORNEY United States l atent O 3,300,679 HlGl-I FREQUENCY ELECTRONDISCHARGE DE- VICE TUNING MEANS HAVING MEANS T CONVERT FROM ROTATIONALT0 RECXPRO- CATING MOTION Jack A. Brown, Mountain View, Calif., assigmorto Varian Associates, Palo Alto, Calif., a corporation of CaliforniaFiled Aug. 26, 1964, Ser. No. 392,210 9- Claims. (Cl. 3155.47)

This invention relates in general to high frequency electron dischargedevices and more particularly to klystrons and tuning means therefore.

In the field of high frequency electron discharge devices such as themulti-cavity, broadband klystron continuous research on methods oflowering per unit tube cost while simultaneously improving the resultantend product is being undertaken. The present invention provides multipleadvantages with regard to cost improvement and product enhancement ofmulti-cavity broadband klystrons. Considering the problem ofbroadbanding a high frequency multi-cavity klystron one conventional'design approach would lead one skilled in the art to utilizedifferential cavity dimensions in order to obtain a broadband overallfrequency response. This approach, of course, results in increased perunit cost because of the differing sizes and is therefore not an optimumsolution. Another approach involves utilizing equivalent cavitydimensions and obtaining a broadband frequency response by appropriatecavity tuner means. In each of the above approaches, it is desirable toutilize tuner means (inductive, capactive, combination of inductive andcapactive) in order to cover as wide a range of frequencies as possiblein a single tube as well as employing stagger tuning for broadbandingpurposes. The present invention provides a simplified tuner actuatormechanism in conjunction with a capacitive gap tuner design incorporatedin a multi-cavity klystron which permits utilization of a single driveshaft to vary tuning rate as well as total frequency range for eachcavity on an independent basis. This, of course, permits utilization ofthe tuner actuating mechanism of the present invention in klystronswhich are stagger tuned on a cavity dimensional basis only or onklystrons which are stagger tuned on a tuner basis only or on klystronswhich i are stagger tunedon a combination of the above. The flexiblenessof the tuner actuating mechanism of the present invention is furtherutilizable in capacitive gap tuned klystron oscillators as well asamplifiers and in plural as Well as single cavity klystrons.

The present invention provides novel means for translating rotationalmotion of a single drive shaft into a reciprocating motion of aplurality of tuner drive screws which motion in turn is translated intooscillatory pendulum motion on a plurality of capacitive gap tunerpaddles on an independent basis with regard to tuning rate and totalfrequency range of coverage as well as relative location of centerfrequency f for a plurality of coupled resonant cavities.

It is therefore an object of the present invention to provide animproved high frequency electron discharge device.

A feature of the present invention is the provision of a klystron havingmeans for providing pendulum type motion to a capacitive tuner mountedin a resonant cavity integrated with said klystron.

Another feature of the present invention is the provision of a klystronhaving a plurality of resonant cavities wherein each of said cavitiesare provided with capacitive gap tuner means actuated by a single driveshaft which provides for translation of rotational motion of the driveshaft into a reciprocating motion on a plurality of tuner drive screwswhich motion in turn is translated into oscillatory pendulum motion ofsaid plurality of capacitive gap tuner means on, an independent basiswith regard to tuning rate and total frequency range of coverage as Wellas relative location of center frequency f for said plurality ofresonant cavities.

These and other features of the present invention will become apparentupon a perusal of the following specification taken in conjunction withthe accompanying drawings wherein:-

FIG. 1 depicts a fragmented longitudinal elevational view of a broadbandmulti-cavity klystron amplifier incorporating the features of thepresent invention,

FIG. 2 is a sectional view partly in elevation taken along the lines 2-2of FIG. 1,

FIG. 3 is a sectional view of that portion of FIG. 2 encompassed bylines 33,

FIG. 4 is a fragmentary perspective view partly sectioned depicting thetuner actuating mechanism utilized in the klystron depicted in FIG. 1,

FIG. 5 is a perspective view of the tuner drive screw portion of thepresent invention,

FIG. 6 is an illustrative graphical portrayal of the manipulation andeffect of independent tuner rate control on a resonant frequency vs.drive shaft revolutions characteristic.

Referring now to FIG. 1, there is depicted a multicavity broadbandklystron device 7 having a beam forming and projecting means (electrongun means) 8 dis posed at the upstream end thereof and electron beamcollector means 9 disposed at the downstream end thereof with aplurality of resonant cavities 10, 11, 12, 13 (electromagneticinteraction means) disposed intermediate said gun and collector means invacuum sealed relationship therewith. The input cavity 10 is providedwith suitable electromagnetic energy coupler means 14, preferablycoaxial as shown, and the output cavity 13 is provided withelectromagnetic energy coupler means 15 preferably as shown anddescribed in co-pending US. patent application Serial No. 387,454, filedAugust 4, 1964, by Robert L. Woods and Ulrich Wolff which is assigned tothe same assignee as the present invention. Quite obviously, theparticular electromagnetic energy couplers, beam forming and projectingmeans, interaction means and overall functional characteristics as wellas other portions of the klystron depicted in FIG. 1 may take any of theacceptable prior art constructions of which the literature is replete.

Each of the resonant cavities is provided with a capacitive gap tuneractuating mechanism 24 which includes the generic concept of acapacitive tuner plate 17 as best seen in FIG. 2 which is mounted on apendulum tuner shaft 18 surrounded by vacuum bellows 19 and adapted andarranged for pendulum oscillation in a plane transverse to thelongitudinal axis 20 of the klystron about pivot axis 21 as describedand claimed in co-pending US. patent application Serial No. 387,740filed August 6, 1964, by Oscar C. Lundstrum and assigned to the sameassignee as the present invention. The tuner plate 17 is preferablyshaped to conform to the exterior geometry of the drift tube 22 and ispreferably disposed symmetrically about a plane which is normal to thetube (device) central axis 20 and equally spaced between the opposedre-entrant drift tubes in each cavity. Quite obviously, the particularrelative dimensions and arrangement of the tuner plate and drift tubescan vary considerably from tube to tube depending on the chosen design.For example, asymmetric gaps and various tuner plate shapes designed forparticular desired characteristics utilizing conventional empiricaldesign techniques are within the purview of the present invention.

The tuner activating mechanism generally indicated by 3 24 includes agear box 25 securely afiixed to, by means of bracket 26, cavity wall 27.The gear box 25 includes two pairs of axially perpendicular verticallydisplaced bores extending through the defining walls of the box and ahollowed interior suitably dimensioned to receive helical translationgears 28, 29 best seen in FIGS. 2,3 and 4. Each helical gear 29 isfixedly mounted, as by press fitting on an elongated drive shaft 30which extends along the longitudinal extent of the tube and which isdriven by means of motor 31 driving bevel gear 32 which in turn drivesbevel gear 33 affixed to the drive shaft 30. A locking collar (notshown) in conjunction with locking bushing 34 retain each helical drivegear 29 in place within the gear box while permitting drive shaftrotation therein. A plurality of set screws such as 35 are preferablyemployed to lock the bushing 34 within the gear box 25. The helicaltuner gear 28 is rotatably secured within the gear box 25 by means of alocking collar 36 in conjunction with tuner nut 37. Locking collar 36 isfixedly secured within gear box 25 to the tuner shaft by means of dowelpin 38 and aset screw 39. Tuner nut 37 is provided with internal threads40 and a smooth external surface 41 and is press fitted within helicaltuner gear 28 such that rotation of the tuner gear 28 will result inrotation of the tuner nut 37 without slippage over the tunable band ofeach cavity.

A tuner drive screw 42, best seen in FIGS. 3 and 5, having externalthreads 43 on both the enlarged main body portion 44 and the reducedneck portion 45 and an elongated generally rectangularly shaped slot 46extending along a major portion of the enlarged main body portion 44 isthreaded within tuner nut 37 and locked therein with respect torotation. relative to the gear box by means of dowel pin 38 extendingthrough elongated slot 46. Tuner drive screw 42 is capable of linear onedimensional non-rotational reciprocating motion by virtue of elongatedslot 46 which prevents rotation of the screw while translating therotational engagement of tuner nut threads 40 and tuner drive screwthreads 43 into'linear reciprocating motion of the tuner. drive screw.The length of the slot 46 functions as a built-in limit stop meansserving to define the extent of linear motion 0 the tuner drive screw42.

The reduced neck portion 45 of the tuner drive screw serves inconjunction with annular clamping nut 47 as a ball joint 48 retaining aspring loaded spherically (ball) tipped drive rod 49. The .ball tip end5t of drive rod 49 is disposed in a matching socket portion of theclamping nut while the other end of drive rod 49 engages tuner pendulumshaft 18 in a slotted end portion 51 thereof, as best seen in FIGS. 2and 4, by means of screw, washer and nut combination 52. The slotted endportion 51 of the tuner pendulum shaft 18 is provided with four 90 spacerotated elongated slots 51' as best seen in FIGS. 2 and 4 which permitadjustment of the point of engagement between the drive rod 49 and tunerpendulum shaft 18 along the longitudinal extent of the pendulum shaft.The extent of this adjustment capability is obviously a function of thelength of the aforementionedslots. The drive rod 49 and tuner screw 42combine to function as reciprocating means 16.

The translation of the reciprocating motion of the drive rod intopendulum motion of the tuner shaft is due to the pivotal axis or point21 about which the tuner shaft 18 oscillates in motion akin to apendulum. The pendulum tuner shaft 18 is supported on and within apreferably annular housing collar 55 which with a support bridge 56having a pair of spaced pivot arms 57 and a suitable support bearingshaft 58 serves to securely afiix the shaft 18 with respect to thehousing collar 55 while permitting pendulum motion about pivot axis 21.Many obviously equivalent pivotal mounting arrangements may be utilizedin lieu thereof. See, for example, the arrangements set forth in theaforementioned co-pending application by Oscar C. Lundstrom. It is to beunderstood that the terminology reciprocating motion covers both onedimensional and two dimensional motion of a drive rod such as 49 whichcouples and translates the rotational motion of the drive shaft 30 intothe pendulum motion of the shaft 18. The two dimensional motion of adrive rod such as 49,may the varied according to the type of couplingmechanisms chosen for converting the rotational motion of the driveshaft 30 into the reciprocating motion of the drive rod 49 and accordingto what type of coupling mechanism is chosen for converting thereciprocating motion of the drive rod 49 into the pendulum motion of thependulum tuner shaft 18.

The aforementioned tuner actuating mechanism 24 in operation is capableof providing efiicient mechanical means for converting the rotation ofbevel gear 32 by drive motor 31 into pendulum type motion of a pluralityof capacitive tuners on an independent basis. The frequency range to becovered by each tuner can be easily preset by selection of anappropriate slot length 46 and the rate of tuning easily preset on anindividual cavity basis 'by'selection of appropriate thread pitches fortuner screw 42 and tuner nut 37.

The location 'of the tunable band for each cavity 0 a multi-cavityklystron can be independently preset by any of a number'of ways orcombinations thereof, as taught by the present invention. One methodwould be through selection of an appropriate tuner screw neck length 45in order to preset the location of the tunable band limits. Anotherapproachwould be independent presetting of the location of the point ofengagement between drive rod 49 and the slotted end portion 51 ofpendulum shaft 18 along' the length of slots 51. Another technique wouldinvolve 1 employing staggered physical locations in each tuner gear box25' of the slots 46 in order to presetthe location of the frequency bandof cover-age of each tuner on an independent basis. This techniquewould, of course, require careful design of the press fit between eachtuner nut 37 and surrounding helicalftuner' gear 28 to allow slippagetherebetween upon engagement of dowel pin'38 and each end point oftheslot 46' such that the drive motor torque was adequate tohandlerotation of at least 11 1 slipping engagement, where n number oftuner actuating mechanisms 16 and assuming the worst case, namelystaggering of all slots 46 physically with respect-to each other.Alternative techniques for control of tuning band locationsareindividual selection of drive rod 49 lengths which wouldb'eequivalent to selection of different neck portion lengths 45 of tunerscrew 42. The aforementioned list of techniques for presetting thetunable band limits on an independent basis 'is not meant to be allinclusive but merely to indicate the flexibleness of the presentinvention.

Techniques available for independent control of tuning rate besides theaforementioned control of thread pitches involve independent presettingof pivot point axis 21 relative to end points of the tuner pendulumshaft 18 and/or conversely variation of shaft lengths on an individualbasis. This technique, of course, inherently involves tuning bandlocation as well as tuning rate and this factor must be considered aswell. In effect, the engagement point between drive rod 49 and shaft 18is equivalent to the control of pivot axis location and tuner shaftlength. Another technique for independent control of tuning rate wouldbe pre-selection on an independent basis of helical gear (28, 29)pitches.

Of the aforementioned independent control techniques the preselection oftuner screw 42 pitch and tuner nut 37 pitch is preferred because of therelative ease of insertion of said elements by merely removing a dowelpin 38; unscrewing clamping nut 47 and removing the tuner screw 42 andtuner nut 37 and insertion of replace ment elements.

FIG. 6 depicts an illustrative graphical example of the utilization ofthe independent control features of the present invention with regard toconverting the motion of a single drive shaft 30 into tune-r shaftmotion for a plurality of tuner shafts in a plurality of cavities havingdifferent tuning characteristics. For example, curves A and B aretypical tuning curves for a driver cavity and an output cavity. It isseen that for a given amount of shaft 30 rotation assuming directconversion and no compensation or independent control of the conversionbetween drive shaft revolutions and pendulum shaft movement will resultin a far greater change in output cavity frequency than driver cavityfrequency for a given amount of shaft rotation. Now, utilizing theindependent control features of the present invention, such as forexample, independent selection of thread pitches for each tuner screw 42and tuner nut 37 such that the output cavity pendulum tuner shaft willmove a smaller distance than the driver cavity pendulum tuner shaft fora given amount of shaft 30 rotation it is a simple matter to compensatethe output cavity tuning characteristic such that it substantiallycorresponds to the driver cavity characteristic. See characteristic Bfor an example of this.

Since many changes could be made in the above construction and manyapparently Widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A high frequency electron discharge device having beam forming andprojecting means disposed at the upstream end portion thereof and beamcollector means disposed at the downstream end portion thereof andelectromagnetic interaction means disposed therebetween and coupledthereto in vacuum sealed relationship to form a vacuum envelope for saiddevice, said interaction means including flexible vacuum sealing meanscoupled thereto, said electromagnetic interaction means having at leastone frequency tuning mechanism coupled thereto, said tuning mechanismincluding means for varying the frequency of electromagnetic energyalong the portion of said electromagnetic interaction means to whichsaid tuning mechanism is coupled, means for physically moving saidtuning means along an arcuate path relative to said electromagneticinteraction means in pendulum type motion about a pivot point means,said means for physically moving said tuning means including a pendulumtuner shaft adapted and arranged for oscillation about said pivot pointmeans, means for moving said pendulum shaft about said pivot point meansincluding motion translational means adapted and arranged for convertingrotational motion into reciprocating motion of a reciprocating meanscoupled to said pendulum shaft to thereby drive said pendulum shaft inoscillatory motion about said pivot point means, said pendulum tunershaft having said tuning means coupled thereto at the one end portion ofsaid shaft, said pivot point means about which .said shaft oscillates inpendulum motion being located along thelength of the shaft intermediatethe respective ends of the shaft, said means for moving said pendulumshaft about said pivot point means being coupled to said shaft at theother end portion of said shaft, said pivot point means being locatedexteriorly of the evacuated region formed by said vacuum envelope, saidpivot point means serving to support said pendulum shaft independentlyof said flexible vacuum sealing means, said reciprocating meansincluding a ball joint.

2. A high frequency electron discharge device having beam forming andprojecting means disposed at the upstream end portion thereof and beamcollectormeans disposed at the downstream end portion thereof andelectromagnetic interaction means disposed therebetween and coupledthereto in vacuum sealed relationship therewith, said electromagneticinteraction means having at least one frequency tuning mechanism coupledthereto, said tuning mechanism including means for varying the frequencyof electromagnetic energy along the portion of said electromagneticinteraction means to which said tuning mechanism is coupled, means forphysically moving said tuning means along anarcuate path relative tosaid electromagnetic interaction means in pendulum type motion about apivot point, said means for physically moving said tuning meansincluding a pendulum tuner shaft adapted and arranged for oscillationabout said pivot point, means for moving said pendulum shaft about saidpivot point including motion translational means adapted and arrangedfor converting rotational motion into reciprocating motion of areciprocating means coupled to said pendulum shaft to thereby drive saidpendulum shaft in oscillatory motion about said pivot point, said motiontranslational means including means for converting rotational motionabout a first axis into rotational motion about a second axis displacedfrom said first axis, said rotational motion about said second axisinducing reciprocating motion of said reciprocating means.

3. The device as defined in claim 2 wherein said device further includesa drive shaft coupled to said motion translational means and a motorcoupled to said drive shaft, said motor being mounted on said devicewhereby the torque of said motor is converted into oscillatory motion ofsaid tuner shaft about said pivot po1nt.

4. A high frequency electron discharge device having beam forming andprojecting means disposed at the upstream end portion thereof and beamcollector means disposed at the downstream end portion thereof andelectromagnetic interaction means disposed therebetween and coupledthereto in vacuum sealed relationship therewith, said electromagneticinteraction means having at least one frequency tuning mechanism coupledthereto, said tuning mechanism including means for varying the frequencyof electromagnetic energy along the portion of said electromagneticinteraction means to which said tuning mechanism is coupled, means forphysically moving said tuning means along an arcuate path relative tosaid electromagnetic interaction means in pendulum type motion about apivot point, said means for physically moving said tuning meansincluding a pendulum tuner shaft adapted and arranged for oscillationabout said pivot point, means for moving said pendulum shaft about saidpivot point including motion translational means adapted and arrangedfor converting rotational motion into reciprocating motion of areciprocating means coupled to said pendulum shaft to thereby drive saidpendulum shaft in oscillatory-motion about said pivot point, thecoupling point between said reciprocating means and said tuner shaftbeing adjustable along the longitudinal axis of said tuner shaft.

5.'A high frequency electron discharge device having beam forming andprojecting means disposed at the upstream end portion thereof and beamcollector means disposed at the downstream end portion thereof andelectromagnetic interaction means disposed therebetween and coupledthereto in vacuum sealed relationship therewith, said electromagneticinteraction means having at least one frequency tuning mechanism coupledthereto, said tuning mechanism including means for varying the frequencyof electromagnetic energy along the portion of said electromagneticinteraction means to which said tuning mechanism is coupled, means forphysically moving said tuning means along an arcuate path relative tosaid electromagnetic interaction means in pendulum type motion about apivot point, said means for physically moving said tuning meansincluding a pendulum tuner shaft adapted and arranged for'oscillationabout said pivot point, means for moving said pendulum shaft about saidpivot pointincluding motion translational means adapted and arranged forconverting rotational motion in-to reciprocating motion of areciprocating means coupled to said pendulum shaft to thereby drive saidpendulum shaft in oscillatory motion about said pivot point, said motiontranslational means including a pair of gears coupled together forconverting rotational motion about a first axis to rotational motionabout a second axis displaced from said first axis, one of said pair ofgears being coupled to a tuner nut, said tuner nut having a threadedinternal surface and a tuner screw having an external threaded surfaceengaging said threaded nut surface, said tuner screw and said tuner nutbeing coupled together such that rotational motion of said tuner nut istranslated into reciprocating nonrotational linear motion of said tunerscrew.

6. The device as defined in claim wherein said coupling means betweensaid tuner screw and said tuner nut includes an elongated slot extendingalong a portion of the length of said screw and a dowel pin extendingthrough said slot whereby said tuner screw is prevented from rotationalmotion while being capable of linear reciprocating motion.

7. A high frequency electron discharge device having beam forming andprojecting means disposed at the up stream end portion thereof and beamcollector means disposed at the downstream end portion thereof andelectromagnetic interaction means disposed therebetween and coupledthereto in vacuum sealed relationship therewith, saidelectromagneticinteraction means having at least one frequency tuning mechanism coupledthereto, said tuning mechanism including means for varying the frequencyof electromagnetic energy along the portion of said electromagneticinteraction means to which said tuning mechanism is coupled, means forphysically moving said tuning means along an arcuate path relative tosaid electromagnetic interaction means in pendulum type motion about apivot point, said means for physically moving said tunaing meansincluding a pendulum tuner shaft adapted and arranged for oscillationabout said pivot point, means for moving said pendulum shaft about saidpivot point including motion translational means adapted and arrangedfor converting rotational motion into reciprocating motion of areciprocating means coupled to said pendulum shaft to thereby drive saidpendulum shaft in oscillatory motion about said pivot point, said tunermechanism including a tuner gear box mounted on said device, said gearbox housing said motion translational means, said motion translationalmeans including a pair of intermeshing helical gears mounted within saidgear box, a cylindrical tuner nut having a smooth external surface andthreaded internal surface coaxially disposed within one of said helicalgears, said reciprocating means including a tuner screw having athreaded external surface coaxially threaded within said tuner nut, saidtuner screw having one end portion adapted and arranged to function as aball joint coupler means between said tuner screw and one end of a driverod portion of said reciprocating means, said drive rod having its otherremote end coupled in fixed, yet adjustable relation to said tunershaft.

8. A high frequency electron discharge device having beam forming andprojecting means disposed at the up- :stream end portion thereof andbeam collector means disposed at the downstream end portion thereof andelectromagnetic interaction means disposed therebetween and coupledthereto in vacuum sealed relationship to form a vacuum envelope for saiddevice, said interaction means including flexible vacuum sealing meanscoupled thereto, said electromagnetic interaction means having at leastone frequency tuning mechanism coupled thereto,.said tuningmechanismincluding means for varying .the frequency of electromagneticenergy along the portion of said electromagnetic interaction means towhich said tuning mechanism is coupled, means for physically moving saidtuning means along an arcuate path relative to said electromagneticinteraction means in pendulum type motion about a pivot point means,said means for physically moving said tuning means including a pendulumtuner shaft adapted and arranged for oscillation about said pivot pointmeans, means for moving said pendulum shaft about said pivot point meansincluding motion translational means adapted and arranged for convertingrotational motion into reciprocating motion of a reciprocating meanscoupled to said pendulum shaft to thereby drive said pendulum shaft inoscillatory motion about said pivot point, said pendulum tuner shafthaving said tuning means coupled thereto at the one end portion of saidshaft, said pivot point means about which said shaft oscillates inpendulum motion being located along the length of the shaft intermediatethe respective ends of the shaft, said means for moving said pendulumshaft about said pivot point means being coupled to said shaft at theother end portion of said shaft, said pivot point means being locatedexteriorly of the evacuated region formed by saidvacuum envelope, saidpivot point means serving to support said pendulum shaft independentlyof said flexible vacuum sealing means, said motion translational meansincluding a tuner drive gear coupled to a tuner screw such that rotationof said tuner drive gear induces linear nonrotational reciprocatingmotion of said tuner screw.

9. A high frequency eletcron discharge device having beam forming andprojecting means disposed at the upstream end portion thereof andbeamcollector means disposed at the downstream end portion thereof andelectromagnetic interaction means disposed therebetween and coupledthereto in vacuum sealedrelationship to form a vacuum envelope for saiddevice, said interaction means including flexible vacuum sealing meanscoupled thereto, said electromagnetic interaction means having at leastone frequency tuning mechanism coupled thereto, said tuning mechanismincluding means for varying the frequency of electromagnetic energyalong the portion of said electromagnetic interaction means to whichsaid'tuning mechanism is coupled, means for physically moving saidtuning means along an arcuate path relative to said electromag neticinteraction means in pendulum type motion about a pivot point means,said means for physically moving said tuning means including a pendulumtuner shaft adapted and arranged for oscillation about said pivot pointmeans, means for moving said pendulum shaft about said pivot point meansincluding motion translational means adapted and arranged for convertingrotational motion into reciprocating motion of a reciprocating meanscoupled to said pendulum shaft to thereby drive said pendulum shaft inoscillatory motion about said pivot point, said pendulum tuner shafthaving said tuning means coupled thereto at the one end portion of saidshaft, said pivot point means about which said shaft oscillates inpendulum motion being located along the length of the shaft intermediatethe respective ends of the shaft, said means for moving said pendulumshaft about said pivot point means being coupled to said shaft at theother end portion of said shaft, said pivot point means being locatedexteriorly of the evacuated region formed by said vacuum envelope, saidpivot point means serving to support said pendulum shaft independentlyof said flexible vacuum sealing means, said device being a multi-cavityvelocity modulation tube and said electromagnetic interaction meansincludes a plurality ofcoupled resonant cavities each having at leastone of said frequency tuning mechanisms coupled thereto, a drive shaftextending along the longitudinal extent of said device, each of saidtuning mechanisms being independently coupled to said drive shaft atspaced positions along the axial extent of said drive shaft such thatrotation of. said drive shaft induces independent oscillatory motion ofeach of said tuner 9 10 shafts about the ivot point means in each ofsaid tuner 3,132,280 5/1964 Schmidt 3l55.47 mechanisms in an independentmanner. 3,227,916 1/ 1966 Proskauer 3155.48 3,227,917 1/1966 Nishida3l5--5.48

References Cited by the Examiner UNITED STATES PATENTS 5 HERMAN KARLSAALBACH, P rim'ary Examiner.

2 5 47 9 1953 Litton 315 5 47 P. L. GENSLER, Assistant Examiner.

1. A HIGH FREQUENCY ELECTRON DISCHARGE DEVICE HAVING BEAM FORMING ANDPROJECTING MEANS DISPOSED AT THE UPSTREAM END PORTION THEREOF AND BEAMCOLLECTOR MEANS DISPOSED AT THE DOWNSTREAM END PORTION THEREOF ANDELECTROMAGNETIC INTERACTION MEANS DISPOSED THEREBETWEEN AND COUPLEDTHERETO IN VACUUM SEALED RELATIONSHIP TO FORM A VACUUM ENVELOPE FOR SAIDDEVICE, SAID INTERACTION MEANS INCLUDING FLEXIBLE VACUUM SEALING MEANSCOUPLED THERETO, SAID ELECTROMAGNETIC INTERACTION MEANS HAVING AT LEASTONE FREQUENCY TUNING MECHANISM COUPLED THERETO, SAID TUNING MECHANISMINCLUDING MEANS FOR VARYING THE FREQUENCY OF ELECTROMAGNETIC ENERGYALONG THE PORTION OF SAID ELECTROMAGNETIC INTERACTION MEANS TO WHICHSAID TUNING MECHANISM IS COUPLED, MEANS FOR PHYSICALLY MOVING SAIDTUNING MEANS ALONG AN ARCUATE PATH RELATIVE TO SAID ELECTROMAGNETICINTERACTION MEANS IN PENDULUM TYPE MOTION ABOUT A PIVOT POINT MEANS,SAID MEANS FOR PHYSICALLY MOVING SAID TUNING MEANS INCLUDING A PENDULUMTUNER SHAFT ADAPTED AND ARRANGED FOR OSCILLATION ABOUT SAID PIVOT POINTMEANS, MEANS FOR MOVING SAID PENDULUM SHAFT ABOUT SAID PIVOT POINT MEANSINCLUDING MOTION TRANSLATIONAL MEANS ADAPTED AND AR-